this after russian president putin told germany's chancellor that ukraine should withdraw its military from the eastern and southern parts of the country. president obama will meet with german chancellor angela merkel later today. >>> alarming news about greenhouse gases on our planet. new tests show the level of caon dioxide in our atmosphere is now at its highest in human history. one scientist told the san francisco chronicle, it is time to stop building things with tail pipes and smokestacks. >>> here they are. horses and jockeys getting ready for this weekend's kentucky derby. an unpredictable field this year. almost anybody could win in the two-minute race. prerace coverage begins at noon eastern, 9:00 pacific on nbc sports network. don't miss race coverage beginning at 4:00 p.m. eastern, 1:00 pacific, here on nbc. >>> in health news, a problem that keeps millions of americans up all night. now the fda approved a new pacemaker like device to treat sleep apnea. it happens when throat and tongue muscles relax blocking airwaves. the implant keep the air ways open by zapping them wit